The present invention is related to an oil-spill detection system, and more particularly to an interferometric oil-spill detection system.
Oil spillage could occur in numerous locations such as seabed exploration sites, oil refineries, or areas close to oil tanks and pipelines. The loss of oil causes both capital and environmental damages. In particular, the environmental damage often takes a long period of time to recover. It is desirable to have an automatic oil spill detection system that monitors oil leaks in the early stage and transmits a suitable warning signal to dispatch a rescue effort for repair.
The existing oil spill detection schemes are mostly in two categories, the scanning type and the fixed-location type. The scanning type, usually satellite-based, monitors a large area of many square kilometers. For example the synthetic aperture radar (SAR) has a large coverage over seawater. The SAR imagery previously had some difficulty in distinguishing dark areas and lookalikes from oil spills. The fixed-location oil spill detectors are often buoyantly situated or anchored. Sometimes the buoy is set adrift but its coordinates are controlled by the global positioning system. These fixed-type oil-spill detectors monitor oil spills by chemical or optical means. Chemical reactions usually cause pollution themselves and chemicals are relatively difficult to maintain. Among the optical means, the generation of UV-induced fluorescence and the change of surface reflectivity on surface oil are the two existing oil-spill detection mechanisms. Unfortunately all of the existing detection schemes have one or several disadvantages, such as poor reliability, high power consumption, high cost, difficulties in maintenance, and complexity.
The SAR oil spillage detection technique is aimed for large-area monitoring while those fixed-location buoy detectors are suitable for real-time, prompt spillage warning at the deployed area. However, both the SAR oil detection technique and the fixed-location buoy detector have the disadvantages of high cost, difficulties in maintenance, and complexity. Therefore, it is desirable to design an early-warning type, surface-oil detector by using optical interferometric techniques. Unlike the existing optical schemes, the interferometric technique detects the interferometric images formed by oil thin films or by oil droplets. The interferometric image formation is more related to the oil geometry than its material property. Integrated into a compact circuit board, this technique is relatively simple, reliable, low-cost, and low-power consuming.
It is therefore an object of the present invention to provide an interferometric oil-spill detection system for detecting the existence of surface oil or oil drops in water.
It is further an object of the present invention to provide a relatively simple, reliable, low-cost, and low-power consuming oil-spill detection system.
It is further an object of the present invention to provide an interferometric oil-spill detection system for detecting the existence of oil spillage on a body of water by using interferometric techniques. The interferometric oil-spill detection system includes a light source for providing an incident light to the oil-spilled body of water, an image extraction device for receiving the reflected light from the oil-spilled body of water and recording the interference fringes of the reflected light, and an image process device connected to the image extraction device for determining whether oil spillage exists according to the interference fringes.
Preferably, the light source is an electromagnetic radiation source of any kind in the optical wavelength range. More preferably, the light source is a laser for providing coherent or partially coherent electromagnetic radiation. The light source consists of one or a few optical elements for collimating, focusing, defocusing, shaping, or directing the optical electromagnetic radiation to the body of water.
Preferably, the image extraction device is a one-dimensional charge-coupled-device (CCD) array sensor, or a CMOS linear sensor array, or a two-dimensional array of the same.
Preferably, the image process system is a computer having a computer program capable of processing the interference fringes and determining whether oil spillage exists.
It is further an object of the present invention to provide a method for detecting the existence of oil-spill on a body of water and transmitting a warning signal to dispatch a rescue effort for repair by using an oil-spill detection system comprising a light source, an image extraction device and an image process device. The method includes the steps of sending a light from the light source to the oil-spilled body of water, receiving the reflected light from the oil-spilled body of water, recording the interference fringes by the image extraction system, processing the interference fringes and checking whether the specific interference parameters are above the threshold values pre-programmed in the image process device, and thereby transmitting a warning signal to dispatch a rescue effort for repair when the specific interference parameters are above the pre-programmed threshold values.
In accordance with one aspect of the present invention, the specific interference parameters are fringe intensity, infringe width, and the number of fringes detected from the image sensor.
It is further an object of the present invention to provide an oil-spill detection system for detecting the existence of oil spillage on a body of water by interferometric techniques. The oil-spill detection system includes a light source system and a discerning medium. This light source system includes a light source and one or a few lenses for providing an incident light to the oil-spill on the water of body. The discerning medium has an image sensor for receiving the reflected light from the oil-spilled body of water, and a logic circuit connected to the image sensor for processing the interference light to determine whether oil spillage exists according to the existence of the interference fringes.
Preferably, the discerning medium is an integrated circuit element, which includes the image sensor and a logic circuit monolithically integrated in a semiconductor chip or a compact circuit board similar to the size of a computer interface card powered by a low-voltage power supply or a solar battery.
More preferably, the light source system and the discerning medium are fabricated monolithically in a semiconductor circuit chip or a compact circuit board similar to the size of a computer interface card powered by a low-voltage power supply or by a solar battery.
Preferably, the light source is any coherent, partially coherent, or incoherent electromagnetic radiation source generating radiations at the optical wavelengths.
Preferably, the light source is a laser of any kind providing coherent or partially coherent electromagnetic radiation.
Preferably, the image sensor is a one-dimensional CCD array sensor, or a CMOS linear sensor array, or a two-dimensional array of the same.
It is further an object of the present invention to provide a method for detecting the existence of oil-spill on a body of water and transmitting a warning signal to dispatch a rescue effort for repair by using an oil-spill detection system comprising a light source and a discerning medium, wherein the discerning medium has an image sensor and a logic circuit. The method includes the steps of transmitting an incident light from the light source to an oil-spilled body of water, receiving the reflected light from the oil-spilled body of water by the image sensor of the discerning medium, processing the interference fringes formed by the reflected light and checking whether the specific interference parameters are above the threshold values pre-programmed in the logic circuit of the discerning medium, and thereby transmitting a warning signal to dispatch a rescue effort for repair when the specific interference parameters are above the threshold values.
Preferably, the specific interference parameters are fringe intensity, infringe width, and the number of fringes.
The present invention utilizes two light interference mechanisms, the thin-film interference and the wavefront-splitting interference. It may be best understood through the following descriptions with reference to the accompanying drawings, in which: